The Spanish striker was exiled following Chelsea’s title-winning campaign under Antonio Conte last season, declaring he would never play for the club again despite scoring 22 goals in 42 appearances.

A return to Atletico Madrid was subsequently agreed allowing the 29-year-old to join his former team in January – although after a summer of uncertainty spent in his native Brazil, Costa has some work to do before he returns to full fitness.

Footage shared by future team-mate Fernando Torres shows Costa working out at NineFitness gym – a franchise owned by Torres – where he has been seen working out with a personal trainer in the boxing ring.

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Diego Costa has taken up boxing in a gym owned by Fernando Torres

Costa, whose notoriously combative style of play frequently landed him in hot water in the Premier League, shadowboxed alongside his coach before the pair posed against the ropes smiling.

Torres posted on his Instagram account: "The best trainer in NineFitness, Diego Costa works out in our club with Jesus Garcia Pola."

Chelsea fans might be regretting allowing their former talisman to leave after back-to-back defeats in the Premier League threatened to derail their title defence.

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The Spanish striker agreed a move to Atletico Madrid earlier this year

Footballs that tried other sports

RIO FERDINAND has announced he will take up professional boxing - but he is not the first footballer to venture into another sport.

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Rio Ferdinand (Boxing) - The ex-Manchester United man has announced he will take up professional boxing

"I think we are working 70% less this season. We are having trouble, tactical and physical aspects because we play every two or three days,” Blues manager Antonio Conte said.

"It is impossible to work on physical and tactical aspects, to pay less attention in every detail. At the moment, after two defeats and a draw, I am happy for the commitment and efforts of the players but if you ask me about the last results, I am not happy.